Apparatus for drying combustible solid



May 21, 1963 c. w. WATERMAN, JR 3,090,131

APPARATUS FOR DRYING COMBUSTIBLE SOLID Filed Oct. 28, 1959 2 Sheets-Sheet 1 INVENTOR mmf/jf M5 ATTORNEYS` May 21, 1963 c. w. WATERMAN, JR 3,090,131

APPARATUS FOR DRyrNG COMBUSTIBLE soLID 2 Sheets-Sheet 2 Filed OCT.. 28, 1959 l INVENTOR mw W m3/AMJ Wdow ATTORNEYS United States Patent O 3,090,131 APPARATUS FR DRYING CGMBUSTIBLE SLID Cliord W. Waterman, Jr., Pittsburg, Kans., assigner to Giadys Elizabeth Dunkie as administra-idx ot the estate of Wesley Earl Dunkle Filed Get. 28, 1959, Ser. No. 849,280 6 Claims. (Cl. 3ft-171) This invention relates to improvements in apparatus for removing moisture from lump, granular or other owable type solid materials such as coal, sand, gravel, sawdust, grain, etc. and particularly to such apparatus adapted for use with combustible materials such as coal.

The apparatus of the present invention is designed to carry out a process for drying materials, coal in particular, disclosed in an application vfor patent filed by Gladys Elizabeth Dunkle as administratrix of the estate of Wesley Earl Dunkle, deceased, Serial No. 722,785, filed March 20, 1958, and as an improvement of the apparatus disclosed in that application.

The process disclosed in the Dunkle application involves the subjection of the coal to heat to drive otf the moisture and generate wet steam. This steam is then converted to super-heated dry steam and the generated steam is used as an enveloping atmosphere for the coal during the entire heating process, in order to occlude from the coal an atmosphere which would support combustion. The apparatus disclosed includes means to move coal along an inclined closed passageway to the top of a gravity tower, down which the coal falls, cascading over steam pipes horizontally traversing the tower. The inlet for coal into the inclined passageway and the outlet for steam are closely associated. The coal outlet from the tower is at a higher level than the steam outlet from the inclined passageway so that a vapor-tilled, air-free atmosphere can be maintained.

The general object of the present invention is to provide drying apparatus of this nature which is of improved structure and vwhich will carry out the above-described process more effectively.

A more specific object is the provision of such apparatus having more eiicient heating means so arranged that a more rapid and complete drying can be accomplished.

Another object is to provide drying apparatus having a material ow path in the tower which will insure a periodic change in the coal face presented to the heating means.

A further object is to provide means for re-cycling and re-heating steam generated within the apparatus to obtain and maintain higher and more uniform operating temperatures.

Other objects of the invention will become apparent from the following description of one practical embodiment thereof, when taken in conjunction with the drawings which accompany, and form part of, this specification.

In the drawings:

FIGURE l is a side elevation of drying apparatus incorporating the principles of the present invention, parts being broken away to show interior structure;

FIGURE 2 is a vertical section taken on the line 2-2 of FIGURE l, showing the major portion of the structure in front elevation;

FIGURE 3 is a vertical section on an enlarged scale, taken on the line 3 3 of FIGURE 2, illustrating a gas cooling chamber used with the apparatus; and,

FIGURE 4 is an enlarged detail sectional view illustrating one mounting arrangement `for the infra-red heaters.

In general, the apparatus of the present invention represents an improvement over the apparatus of the abovementioned Dunkle application in the type of heating means used, the arrangement of the heating means relative to the flow path of material through the tower, the structural features of the ow path to cause overturning of the material to effect more complete moisture removal, and the means used to recirculate steam generated by the apparatus.

Referring to the drawings in detail, there is shown a heating tower l, a cooling chamber 2 beneath, and in cornmunication with, the tower, a controlled outlet 3 for processed coal, and an inclined feed conduit 4 to lsupply material to the top of the tower.

The tower 1 may be supported in any suitable framework. This may consist of vertical posts 5 and horizontal frames 6 at appropriate levels to mount the equipment. The feed conduit may also be suitably supported, as by pedestals 7 and has its upper end connected to the tower at the top.

The feed conduit may be any suitable inclosure along which the coal being processed may be moved to reach the top of the tower. The conduit is shown as an inclined housing S forming a passageway Which is rectangular in cross-section. There is a coal-receiver 9 communicating with the housing 8 near its lower end which forms an inlet for the coal. A conveyor I@ of appropriate type is mounted in the conduit. For purposes of illustration, a chain, or `belt type, conveyor having a plurality of spaced pusher blades l1 is shown. The chains 12 pass over sprockets 13 at the top and bottom of the conduit. A motor 14 drives the top sprocket. The coal, entering through the inlet will fall through the chains onto the lower inclined wall of the housing and be carried by the blades 11 to the top of the conduit where it will fall into the top of the tower.

The tower is essentially a vertical enclosure through which the coal iows by gravity. The passage is made tortuous in order to provide for longer and more direct subjection of the coal to the heating means, and to turn the coal repeatedly, in order to present a new coal face to each succeeding heating element.

As the coal falls into the top of the tower, it is spread evenly across the tower area by means of a spreader 15. This can be a pair of chains lo passing over sprockets 17 and carrying a plurality of vanes 18. The device is driven by a motor 19, and the movement of the blades across the entrance throat of the tower will cause lateral movement of the entering coal to spread it over the entire tower cross-sectional area.

The tortuous coal path through the tower is achieved by providing a plurality of declining shelves 20, positioned beneath one another in opposite relation to provide a zig-zag pattern through the major portion of the tower. While it is essential only that the shelves be inclined, each shelf may be formed as part of a tiltable heatercarrier 21, pivotally mounted at at 22. The carrier and the tower wall will have matching arcuate wall sections 23 and 24, to permit swinging movement of the carrier about its pivot while maintaining a tight enclosure. The tower wall sections 2?:y will be spaced apart, and the intermediate section of the carrier Wall will serve to mount heating elements 25. Thus, the heating elements can be positioned directly opposite the shelves and maintained in that position even though the angle of the shelves is adjusted. Where the above-described carrier arrangement is used, the side Walls of the tower adjacent the upper ends of the shelves will be inwardly and downwardly extended to provide lips .26 to overlie the shelf ends to prevent coal faliing behind the shelves.

The shelves 20` may be provided -with transverse gutters 27 to facilitate drainage Ito the outer edges of the tower where it will be collected by a vertical conduit 28 emptying into a suitable water seal 2S located at the base of the tower. The gutters may be covered by wire mesh screens 27 to prevent entry of coal particles. lt has been noted that application of infra red causes, by elec- -of angle members arranged as inverted Vs.

3 intromagnetic attraction, extractions of water from the interior of the coal .to the surface Vwhere it appears as beads. By collecting this moisture in the gutters at each stage of drying, together with moisture condensed by in` coming cool coal from rising hot vapors, operating costs will be substantially lowered. if this condensa-te can be removed as free water, it will not be necessary to use the added power necessary to regenerate it to steam.

it is contemplated that the heating elements will be infra red ray generators. These may be any of those commonly known, such as :the gas heated ceramic type. The use of the infra red generators as heating means provides several advantages: The heating means may be mounted outside the coal flow path, thus providing i'or obstruction-free `flow of `the coal; the infra red generators provide a more eicient heating medium for building internal heat in high moisture lignite coal than the steam pipes disclosed in the above-mentioned Dunkle application; and, the high absorption rate of the infra red coupled with the generated steam provided for highly efficient moisture removal at low cost. It has been found that the generators 25 may be mounted in rows along the carrier walls for most advantageous results.

The present invention provides for recycling and re-use of the steam generated in the tower. To tl is end, a re- Aturn pipe 29 is in communication with the tower above the spreader l5. A portion of the steam rising in the tower will pass out through pipe 29, under the iniiuence of circulating fan 29 to be returned to the tower below the bottom shelf 2d for recirculation. Some means for reheating the steam will be included in the re-cycling line. This can conveniently take the form of an infra red heat exchanger, shown diagrammatically at Sii. Thus, dry steam will enter the base of the tower and move upwardly, counter to the tlow of coal.

After passing through the tower, the coal is moved through a cooling chamber. The chamber shown consists of a cylindrical housing 3l having a plurality of horizontally positioned bathes 32. These may take the form The end wallsof the cooling chamber may be aperturcd, as at 33, in alignment with the ends of some ot the baliles 55, so that these battles can serve as open conduits for washed ilue gas from Va scrubber (not shown). The flue gas not only cools the coal, but carries away residual surface moisture.

The cooler shown is merely illustrative of any suitable cooling means. The cooler is not part of the present invention, but is shown in order to disclose a complete machine.

From the cooler the coal will pass through any suitable controlled outlet 3. This may be -a Valve 34 operated by a motor 35 to provide a periodic opening `and closing of the valve. The rate of discharge of coal through the outlet 3 is used to determine and control the coal flow rate through the drying tower.

In order to adapt the device .to the system ldisclosed in the Dunkle application, the coal receiver is provided with some means for admitting the coal while preventing the free escape of steam. This can be a simple star feeder indicated diagrammatically at 36. A steam outlet 37 is provided below the coal inlet, so that all portions of the feeder conduit and the tower in which coal is present may be lled with steam to occlude all air which might support combustion.

In using the apparatus, coal is introduced into the receiver 9 and then to the conduit 4. The conveyor will carry the coal to the top of the tower and empty it into the tower where it will be spread by the spreader 15. The coal will then iow down the top shelf 20, where it will be subjected to the heat from the adjacent banks of infra red generators 25. As the coal drops from the lower end of the top shelf onto the lip 26 and thence onto the next shelf, the coal will be turned, thus presenting a new face to the next succeeding infra red generator. This reversal of position and presenting of a new face will occur at each stage of the downward zig-zag passage through the tower. As the internal heat of the coal is built up driving out the moisture, the free water ill run oit through gutters 27 and steam will be generated of the remaining moisture so that the tower \will become completely steam filled. This steam will rise and about fifty percent of it will enter the return pipe 29. The remainder will iiow out through the conduit `ri thus filling that passageway also. The steam flowing down the conduit d lwill serve to preheat the entering coal. This portion of the steam will tlow out of the system through the outlet 37. That portion of the steam which enters the re-cycling pipe 29 will be re-heated by passage through the heat exchanger 31? and converted into dry steam. The dry inert steam then passes upwardly through the coal bed and mingles with the saturated steam from the drying coal. Both steams regenerate to dry steam as they pass through the infra red sections. 'lire coal passes down the tower from one shelf to another at a rate :determined by discharge of coal from the outlet. Each time the coal drops from one shelf to the next, it reverses its direction and is turned over to bring different surfaces to the infra red heaters. if it is found that the coal is sticking to the shelves, or tiowing too freely, the carriers may be adjusted to vary the shelf angle.

While in the above one practical embodiment of the in- Vention has been disclosed, it will be understood that the details of structure shown and described are merely by way of example and the invention may take other forms within the scope of the appended claims.

What is claimed is:

l. Apparatus for drying moisture containing combustible solids comprising an enclosed tower having an inlet at the top and an outlet at the bottom, an upwardly directed conduit having an inlet for solids near the bottom and an outlet for solids at the Itop communicating with the inlet -to the tower, means to elevate solids to the top of the upwardly directed conduit, means forming a zigzag `liow path for solids through the tower from the tower inlet to the tower outlet so that a mass of solids moving along the low path will be caused to reverse its travel direction and expose a different mass surface at each direction change in the path, infrared generators mounted along the iiow path in positions to act upon the solids after direction change of the mass to heat the solids and generate steam in the tower to fill the tower and conduit, an outlet for steam communicating with the conduit at a level below lthe outlet from the tower, and a steam recycling line connected into the tower :adjacent the inlet end and adjacent the outlet end to permit ow of steam from the toiwer adjacent the inlet end to the tower adjacent the outlet end.

2. Apparatus for drying moisture containing combustible solids comprising an enclosed tower having an inlet at the top and an outlet at the bottom, an upwardly directed conduit having an inlet for solids near the bottom and an outlet for solids at the top communicating with the inlet to the tower, means to elevate solids to :the top of the `upwardly directed conduit, means forming a zig-zag flow path for solids through the tower from the tower inlet to the tower outlet so that a mass of solids moving along the flow path will be caused to reverse its travel direction and expose a diierent mass surface at each direction change in the path, infra red generators mounted along the flow path in positions to act upon the solids after direction change of the mass to heat the solids and Vgenerate steam in the tower to ill the tower and conduit,

an outlet for steam communicating with the conduit at a level below the outlet from the tower, a steam re-cycling line connected into the tower adjacent the inlet end and adjacent the outlet end to permit flow of steam from the tower adjacent the inlet end to the tower adjacent the outlet end, and a heating means forming part of the recycling line to re-heat the steam before re-entry into the tower.

3. Apparatus for drying moisture containing combustible solids comprising, an enclosed tower having an inlet at the top and an outlet at the bottom, an upwardly directed conduit having an inlet for solids near the bottom and an outlet for solids at the top communicating with the inlet to the tower, means to elevate solids to the top of the upwardly directed conduit, a plurality of carriers vertically spaced within the tower, each carrier having a declining shelf portion with the carriers arranged so that solids owing over the shelf of one carrier will fall onto the shelf ofthe carrier below, infra red generators carried by each carrier spaced from the shelf and directed toward the shelf to heat solids owing over the shelf to generate steam in the tower to lill the tower and conduit, an outlet for steam communicating with the conduit at a level below the outlet from ,the tower, a steam re-cycling line connected into the tower above the topmost of the vertically spaced carriers and below the lowerrnost of the carriers `to permit ow of steam from the top of the tower to the bottom of the tower, and means in the re-cycling line to re-heat steam passing through the line.

4. Apparatus for drying moisture containing combustible solids comprising, an enclosed tower having an inlet at the top and an outlet at the bottom, an upwardly directed conduit having an inlet for solids near the bottom and an outlet for solids at the top communicating with the inlet to the tower, means to eleva-te solids to the top of the upwardly directed conduit, `a plurality of carriers vertically spaced within the tower, each carrier having a declining shelf portion with the carriers arranged so that solids flowing over the shelf of one carrier will fall onto the shelf of the carrier below, infra red generators carried by each carrier spaced from the shelf and directed toward the shelf to heat solids ilowing over the shelf to generate steam in the tower to lill ,the tower and conduit, an outlet for steam communicating with the conduit at a level below the outlet from the tower, each of said shelf portions having a transverse gutter to carry 0E free Water, :and a collection pipe connecting the gutters.

5. Apparatus for drying moisture con-taining combustible solids comprising, an enclosed tower having `an inlet at the top and an outlet a-t the bottom, an upwardly directed conduit having `an inlet for solids near the bottom and an outlet for solids at the top communicating with the inlet :to the tower, means to elevate solids to the top of the upwardly directed conduit, a plurality of carriers vertically spaced within the tower, each carrier having a. declining shelf portion with the carriers 4arranged so that solids iiowing over the shelf of one carrier Will fall onto the shelf of the carrier below, infra red generators carried by each carrier spaced from the shelf and directed toward the shelf to heat solids ilowing over the shelf Ito generate steam in vthe tower to ll the tower and conduit, and an outlet for steam communicating with the conduit at a level below the outlet from the tower, the carriers being angularly adjustable to vary the inclination of the shelf portion, whereby the shelf portions of the carriers and the infra red generators carried by the carriers will be moved as units to change the shelf angle without varying the positions of the infra red generators relative to the shelf.

6. Apparatus for dryino moisture containing combustile solids as claimed in claim 5 wherein, each or" the shelf portions has a transverse gutter to carry off free water, and a collection pipe connects the gutters.

References Cited in the tile of this patent UNITED STATES PATENTS 2,020,504 Hantla Nov. 12, `1935 2,545,850 Imhoff Mar. 20, 1951 2,610,412 Rasmussen Sept. 16, 1952 2,735,806 Mora Feb. 21, 1956 

1. APPARATUS FOR DYING MOISTURE CONTAINING COMBUSTIBLE SOLIDS COMPRISING AN ENCLOSED TOWER HAVING AN INLET AT THE TOP AND AN OUTLET AT THE BOTTOM, AN UPWARDLY DIRECTED CONDUIT HAVING AN INLET FOR SOLIDS NEAR THE BOTTOM AND AN OUTLET FOR SOLIDS AT THE TOP COMMUNICATING WITH THE INLET TO THE TOWER, MEANS TO ELEVATE SOLIDS TO THE TOP OF THE UPWARDLY DIRECTED CONDUIT, MEANS FORMING A ZIGZAG FLOW PATH FOR SOLIDS THROUGH THE TOWER FROM THE TOWER INLET TO THE TOWER OUTLET SO THAT A MASS OF SOLIDS MOVING ALONG THE FLOW PATH WILL BE CAUSED TO REVERSE ITS TRAVEL DIRECTION AND EXPOSE A DIFFERENT MASS SURFACE AT EACH DIRECTION CHANGE IN THE PATH, INFRA RED GENERATORS MOUNTED ALONG THE FLOW PATH IN POSITIONS TO ACT UPON THE SOLIDS AFTER DIRECTION CHANGE OF THE MASS TO HEAT THE SOLIDS AND GENERATE STEAM IN THE TOWER TO FILL THE TOWER AND CONDUIT, AN OUTLET FOR STEAM COMMUNICATING WITH THE CONDUIT AT A LEVEL BELOW THE OUTLET FROM THE TOWER, AND A STEAM RECYCLING LINE CONNECTED INTO THE TOWER ADJACENT THE INLET END AND ADJACENT THE OUTLET END TO PERMIT FLOW OF STEAM FROM THE TOWER ADJACENT THE INLET END TO THE TOWER ADJACENT THE OUTLET END. 